1. Field of the Invention
This invention relates to data processors and power supply apparatuses for the same, and particular to a data processor which accesses to memory means to write or to read data, and a power supply apparatus for the data processor which is powered by a power supply which supplies power to the data processor and the other loads
2. Related Art
Recently, various types of data processors such as personal computers have been developed so as to deal large amount of data and to realize high process performance. These kinds of data processors can be operated by built-in battery without commercial power supply. In this case, since operation time is restricted by the battery, it is difficult to operate long time and therefore it needs to interrupt the operation for exchanging the battery or charging the battery. However, in a case where such the data processor is used in a particular place, which has a battery having an electric generator, such as vehicle, the operation time can be prolonged by supplying power to the data processor from a vehicle-mounted battery.
Particularly, when the personal computer is used in the vehicle for professional purpose, it is necessary to use the vehicle-mounted battery. However, in this case, when the vehicle-mounted battery is used to start up an engine or a drive motor, a terminal voltage of the vehicle-mounted battery may temporally fall due to large electric current flowing therein. Furthermore, in this case, a start-up time of the personal computer may be prolonged.
In detail, generally, in such the data processor to be mounted in the vehicle, many data including operation system (OS) as basic software, device driver software for controlling peripheral devices to be connected to the data processor, and plural application software (program), are installed in the data processor. As the operation system, there are basically two types. One is a general purpose OS for being installed in the data processor; and another is special purpose for being installed in the peripheral device. Here, it is preferable to apply the general purpose OS, from a viewpoint of extensibility so that the data processor may connect various types of peripheral devices.
However, in general, total file size of such the general purpose OS is large. Therefore it needs to use large capacity hard disk unit (HDD unit) to store such the general purpose OS, and it takes certain time to load the OS from the HDD unit. In this case, when the power supply voltage falls during accessing the HDD unit, the HDD unit may be damaged.
The above-described technical problems are summarized as follows.
First, in the case where the power is supplied to the data processor even during the engine""s start-up, the data processor may not be able to complete the start-up when the engine cannot start up, because the power supply from the vehicle-mounted battery is stopped. Furthermore, when the power supply is interrupted as a result of exchanging the vehicle-mounted battery while the data processor operates, the HDD unit may be also damaged.
Second, when the data processor is mounted on a commercial vehicle as a vehicular terminal apparatus for, for example, the commercial vehicle, the total file size of the software to administrate process may become large. In the case where such the large software is used, when a system in which the vehicular terminal apparatus is started up every time the engine starts up is used, a total start-up time may be prolonged. Furthermore, it needs to provide means for performing a stop-reset (reset by turning off) by hardware to the vehicular terminal for preparing for undesirable defect of the HDD unit.
Third, in the case where the data processor is started up simultaneously with the engine""s start-up, the data processor is turned off simultaneously with the engine""s stop. However, in this case, when the data processor accesses to the HDD unit when the engine is stopped, the HDD unit may be damaged.
Fourth, in the case where the data processor can be operated even when the engine stops, the vehicle-mounted battery is used without being changed. Therefore, consumption of the vehicle-mounted battery may be facilitated, and the start-up of the engine may be harmfully influenced as a result.
This invention has been conceived in view of the background thus far described and its first object is to provide a data processor or a power supply apparatus for a data processor capable of preventing from causing a harmful influence due to an operation of the other loads, even when the data processor or the power supply apparatus for the data processor is powered by a battery, which is commonly used by the other loads.
Its second object is to provide a data processor or a power supply apparatus for a data processor capable of preventing an inconvenience in connection with a long start-up time.
According to the present invention, when the other loads, which is powered by a main power supply, is started up, the start-up circuit detects a stable condition of an output voltage from the main power supply. When the start-up circuit detects the stable condition of the output voltage from the main power supply, a power supply controller starts supplying the power from the main power supply to the data processor. In this case, even if power is supplied to the data processor while the other loads is being started up, the data processor can be started up from the stable condition after a unstable condition due to the start-up of the anther load. As a result, it can prevent from causing a harmful influence due to an operation of the other loads.
According to another aspect of the invention, the power supply controller measures a power supply time to the data processor, and restarts the data processor when the power supply time exceeds a predetermined time. As a result, it can prevent an inconvenience in connection with a long start-up time.